<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
	</head>
	<body>
		<div id="example">
		</div>	
		<script>
			let data={a:1};
			let vm=new Vue({
				el:'#example',
				data:data
			})
			console.info(vm.$data==data);
			console.info(vm.$el === document.getElementById('example'))
			
			vm.$watch('a',function(newValue,oldValue){
				console.info('a改变啦,beforeValue:%s,afterValue:%s',oldValue,newValue);
			});
			vm.a=3;
		</script>	
	</body>
</html>
